In some cases - where developers are being unco-operative and NAMA believes they are hiding the full extent of their properties and other assets - it has threatened enforcement proceedings.
When developers submit business plans to NAMA they are obliged inform the agency of their assets and frequently asked to provide tax returns.
By matching tax paid on rental income to the list of properties, the agency can see if the developers have been honest and declared all their assets.
However, according to RTÉ, some developers have refused to submit tax returns.
A spokesman for NAMA said failure to give information prompted a credit check to see if developers had undisclosed assets. If NAMA finds that a developer is being unco-operative, it can take enforcement proceedings against the borrower.